Which one of the following is a complex sentence?

A. I would like to visit the Kinshasa, but I understand the city is unsafe for foreigners.

B. As Jake was reading the letter from June yet again, the flight attendant t coughed gently to get his attention.

C. Check out the editorial page in today's paper and you'll notice the piece by Oscar Lewis.

D. I simple cannot make heads or tails of rap lyrics, but I suppose I'm just too old to understand them.

Answer is "B"

Right.